When it came time to pull the worn-out, 150,000+ miles 4.8L V-8 out of the '04 GMC Sierra we nicknamed Project Novakane, we didn't want a little more power, we wanted monster power. Thankfully, making big power out of a relatively small engine is as easy as intelligently choosing the right combination of engine, power adder, drivetrain, and also understanding the limits to which you can push your combo. This part of the buildup was the most intense, most heavily researched, and most exciting, after all, the engine is the heart and soul of a performance truck.

Before we could dream of burnouts and high-speed conquests, we first needed to remove the tired original 4.8L. To do this, we drove the Sierra into our Source Interlink Tech Center and got to work removing the necessary parts. Working on a '99+ GM truck is quite easy and pulling the engine, with the right tools and some help, isn't a difficult job. We started by removing the hood, then drained the coolant, and began the job of removing the serpentine belt, alternator, throttle body, and intake manifold. Each bolt that was removed was placed in a Ziploc bag and cataloged for easy reference when the new engine is installed. On the GM trucks, a cool trick is simply unbolting the A/C compressor and bracket, along with the power steering pump and bracket, and swinging them aside without disconnecting the hoses, which would require a costly flush and refill. With each sensor disconnected and wire labeled for reference, we removed the driveshaft, disconnected the manual transmission shifter, and unbolted the transmission and engine mounts, along with the front crossmember, and then bolted the engine leveler to the block. A couple of tugs with the engine hoist later, our 4.8L was out of the truck and our Sierra was ready for some real power!

Looking around the performance car world, one particular supercar stood out time and time again-the LS9-equipped Corvette ZR1. Combining a supercharger with the tried and true (albeit modified and reinforced) LS3 under the hood, the new engine helps the ZR1 outperform other cars costing twice as much. Backing the blown small-block is a heavy-duty Tremec six-speed that helps propel the 'Vette to incredible performance numbers. Knowing that the GM Performance engineers are some of the best in the world, we're going to use the ZR1 as inspiration for Project Novakane. Hunting around for an appropriate long-block, we came across GM Performance Parts newest member of the LSX family, the LSX376. We officially had our first "lightbulb" moment and knew this engine was going to power our 4,300-pound truck into warp speed for the long haul.

Starting with an economical LSX Bow Tie block, the GM Performance Parts engineers added high-flow LS3-style L92 heads and 9:1 low-compression forged-aluminum pistons for a boost-friendly, high-revving engine that packs a wallop in a 376ci small-block package. Using the stock LS3 fuel-injection manifold and throttle-body, the LSX376 creates 450 hp at 5,900 rpm and 444 lb-ft of torque at 4,600 rpm, however, with the low-compression pistons, boost is what this engine lives for. Designed for 6-8 psi of boost, the LSX376 can safely live around the 620 hp range and still deliver nearly 20 mpg on the highway. If boost is what the LSX376 wants, then boost is what we'll give it.